Flexible sound record



FLEXIBLE SOUND RECORD Filed Aug. 29, 1929 WON-INFL HMMABLE CELLULDSEMATE/EVIL NIMOCELL ULDSE MATERIAL IMPRES/VATEU PAPER 0R AR c mg;NUN-INFLAMMABLE C ELLIIL'USE MATERIAL.

MIXTURE 0F NITROP C ELLULOSE MATERIAL [AND )VfllV-lA/FL/IMMABLE ClLULO$MATERIAL.

IMPREGNATED PAPER 0R FABRIC CORE.

' gwumtoz duoawwm Patented Apr. 9, 1935 I UNITED STATES FLEXIBLE ,SOUNDRECORD Samuel Whyte, Redhill, England, assignor, by mesne assignments,to Radio Corporation of America, New York, N. Y., a corporation ofDelaware Application August 29, 1929, Serial No. 389,328 In GreatBritain September 11, 1928 2 Claims. (01. 154-43) The present inventionrelates to laminated disc 5 lose acetate or the like.

The object of the present invention is to effect improvements in arecord of this type whereby the surface noise is considerably reducedwithout the wearing qualities being adversely afiected.

It has been found that this object is attained if both nitro-celluloseand cellulose acetate or other non-inflammable cellulose material areemployed-for the outer films of the sound record. Thus the improvedrecord according to the present invention comprises a paper or fabriccore to each side ofwhich is attached firstly a layer of non-inflammablecellulose material and then a layer of nitrocellulose material or viceverse...

Alternatively only one layer consisting of a mixture of non-inflammablecellulose, material and nitro-cellulose is attached to each s de of thecore.

The core is preferably treated with a waterproofing or bindingcomposition and the layers of non-inflammable cellulose material andnitrocellulose material may both be applied in the form of a solution orof thin sheets or films, or one of the layers may be applied as asolution and the other as a sheet. It is also preerable that the variouslayers should have substantially the same coefiicients of expansion.

The invention is illustrated diagrammatically in the accompanyingdrawing, Fig. 1 showing one form of record blank having separate layersof nitro-cellulose material and non-inflammable cellulose material, andFig. 2 showing another form of record blank having a layer which is amixture of these materials.

In one method of carrying out the invention, a paper core approximately.01 inches thick is impregnated with paraiiin wax, metal stearates,rosin, bituminous compounds or other material which will leave the paperwaterproof after the applicat on of heat and pressure. and which shouldgive to the core a similar coeflicient of expansion to that of thesurface material; otherwise the surace of the record, will developunevenness and sufier in appearance and quality of surface noise. Then asolution of nitro-cellulose conta ning rosin is applied to the core.When the core is dry, a sheet of cellulose acetate materialapproximately .003 to .005 inches thick is applied to each side of thecore. The whole is then -hot pressed between the matrices carrying therequired records.

In another method, a paper core is first impregnated with either anaqueous or an alcoholic solution of urea or thiourea formaldehyde resinsor phenol formaldehyde, or other synthetic resin mixed with or withoutcolouring matter or filler the paper being squeezed thereafter betweenrollers to assistimpregnation and to remove excess of solution. Theimpregnated paper is then dried at a suitably low temperature and spreadwith nitro-cellulose solution. The coating of nitrocellulose solution isdried, and covered with the cellulose acetate material intended to formthe playing surface of the record as in the first described method.

In a modification of the last method, the cellulose acetate material isapplied in the form of a solution. The cellulose acetate may bedissolved in acetone or other ketones or mixtures of acetone with any ofthe known solvents ,for celiulose esters, together with a suitableproportion of dissolved plasticizer such as p-toluene sulphonamide,diethyl phthalate or the like and with or without pigment, dyes orfilling materials such as zinc oxide, lithopone, barytes, carbon black,nigrosine or the like. Various resins may also be incorporated ifdesired. For example, a suitable solution is prepared by dissolving 1220gms. of powdered cellulose acetate together with 260 gms. ofpara-toluene sulphonamide in 7 litres of a mixture of acetone (75%),alcohol (10%) and benzol (15%) to form a dope of suitable con-.

sistency for spreading and 480 gms. of lithopone incorporated therewith.After drying and seasoning the coated core, the whole is hot pressedbetween the matrices carrying the required records.

The nitro-cellulose solution used in the above examples preferablyconsists of the lower nitrates of cellulose dissolved in acetone orother ketones or esters such as ethyl acetate or butyl acetate, togetherwith a plasticizer such as triphenyl phosphate. This solution may alsocontain various fillers or pigments such as zinc oxide, barytes or thelike and various resins may be incorporated. For example, anitrocellulose solution suitable either for the surface of the record oras an undercoating to the surface is prepared by dissolving 1300 gms. ofnitrated cotton together with 200 gms. of triphenyl phosphate in 7litres of a mixture of acetone (75%) alcohol (10%) and benzol 15%) toform a dope of suitable consistency for spreading and 500 gms. of zincoxide are incorporated therein.

If the layer next to the paper core is applied in the form of asolution, then it may not be necessary to impregnate the core with anywaterproofing composition, although, especially in the case plied in theform of solid layers or sheets, apaper core smaller in diameter than thefinished discs may be used. For example, the core may be 9.75? indiameter for a 10" record. In this case, a secondary operation isnecessary. to press together the overhanging portions of the outer filmsof cellulose material. This pressing together of the overhanging edgesforms a seal which prevents atmospheric or other moisture from reachingthe core, and if paper with a suitable finis and sizing is used for thecore, impregnating with a wax or resin is unnecessary.

The term fibrous material as employed in the claims includes paper orfabric and the like.

I claim:

1. A sound record blank comprising a core of fibrous materialimpregnated with a urea formaldehyde resin and having attached thereto aplurality of layers of material at least one. of which constitutes therecord surface and includes a noninfiammable cellulose ester, thecoeflicients of expansion of each of said layers being substantially 10equal.

2. A sound record blank comprising a core of fibrous materialimpregnated with a urea formaldehyde resin and having attached thereto.a plurality of layers of material at leastone of which 15 constitutesthe record surface and includes a non-inflammable cellulose ester.

SAMUEL WHYTE.

